Resistance seam welding is known in the art for joining metal workpieces. The workpieces may be stacked or otherwise held in temporary assembly. The workpieces are then clamped between a pair of roller electrodes, which locally compress the workpieces. The electrodes are energized, causing electrical current flow through the workpieces to locally heat the workpieces between the electrodes and thereby form a weld. During this time the workpieces and the rollers are moved relative to one another to elongate the weld and thereby form a seam weld between the workpieces.
Roller electrodes commonly have a larger contact area than conventional electrodes, which distributes welding current over a larger workpiece area. Thus a greater flow of electric current is required than with conventional electrodes to heat the larger area and form a weld. The larger contact area of a roller electrode also creates welding limitations when the workpieces to be joined are contoured or non-planar. In addition, roller wheels must be turned as they are moved relative to the workpieces to create a curved or angled seam weld.
Thus, it is desirable to provide a resistance seam welding electrode which provides a smaller contact area than conventional rollers to reduce electric current requirements. It is also desirable to provide an apparatus for resistance seam welding having electrodes adapted for universal directional motion to conform to any desired weld pattern or part shape.